U.S. patent number 6,141,879 [Application Number 08/962,370] was granted by the patent office on 2000-11-07 for cord type grass-cutting head with means for preventing the entry of waste matter.
This patent grant is currently assigned to Arnetoli Motor di Arnetoli Fabrizio. Invention is credited to Fabrizio Arnetoli.
United States Patent |
6,141,879 |
Arnetoli |
November 7, 2000 |
Cord type grass-cutting head with means for preventing the entry of
waste matter
Abstract
The cord-type grass-cutting head includes a container (3, 4)
having arranged inside it at least one reel (5) of cutting cord
(F), the ends of which emerge from holes in the container, and an
operating mechanism for controlled unwinding of the cord from the
reel, which mechanism comprise a sliding actuating member (17, 19)
projecting from the container, a slit being defined between the
sliding member and the container. A flexible protective membrane
(33) covers the slit between the sliding member (17, 19) and the
container (3, 4).
Inventors: |
Arnetoli; Fabrizio (Florence,
IT) |
Assignee: |
Arnetoli Motor di Arnetoli
Fabrizio (IT)
|
Family
ID: |
11352211 |
Appl.
No.: |
08/962,370 |
Filed: |
October 31, 1997 |
Foreign Application Priority Data
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Jul 18, 1997 [IT] |
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FI97A0171 |
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Current U.S.
Class: |
30/276;
56/12.7 |
Current CPC
Class: |
A01D
34/4163 (20130101) |
Current International
Class: |
A01D
34/412 (20060101); A01D 34/416 (20060101); B26B
007/00 (); A01D 034/67 () |
Field of
Search: |
;30/276,347
;56/12.7,12.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Peterson; Kenneth E.
Assistant Examiner: Choi; Stephen
Attorney, Agent or Firm: McGlew and Tuttle, P.C.
Claims
What is claimed is:
1. A cord-type grass-cutting head including:
a container;
at least one reel of cutting cord housed in said container with
ends of said cutting cord projecting out from holes in said
container;
a cover arranged on said container;
at least one aperture with an edge portion in said cover;
operating means for controlled unwinding of said cord from said
reel, said operating means including a sliding actuating member
which projects out from said container through said at least one
aperture so that a slit is formed between said edge portion of said
at least one aperture and said sliding actuating member;
a flexible membrane having at least a first rim connected to said
cover along said edge portion and a second rim connected to said
sliding actuating member to seal said slit and block penetration of
waste matter into said slit so that said aperture is completely
sealed, said flexible membrane being connected to said cover and
said sliding actuating member for flexural deformation of said
flexible membrane during sliding of said sliding actuating
member.
2. A grass-cutting head according to claim 1, wherein said flexible
membrane forms a portion of a protective cap fitted onto the cover,
which cap covers a sliding seat of said sliding actuating
member.
3. A grass-cutting head according to claim 2, wherein said
protective cap comprises a substantially rigid annular flange with
means for attaching the flange to said cover and a substantially
rigid central portion co-operating with said sliding actuating
member, said flexible membrane joining said annular flange and said
central portion.
4. A grass-cutting head according to claim 1, wherein said flexible
membrane is made of plastic material which is molded together with
the cover of said container along said edge portion and together
with said sliding actuating member.
5. A grass-cutting head according to claim 1, wherein said flexible
membrane is made of plastic material which is molded together with
the cover and has a central portion co-operating with said sliding
actuating member.
6. A grass-cutting head according to claim 1, wherein said flexible
membrane has an annular portion and is integrally formed at
respective opposite ends with two substantially rigid cylindrical
portions fixed to said cover and said sliding actuating member,
respectively.
7. A grass-cutting head according to claim 6, wherein said
cylindrical portions are engaged with the container and the
operating means by force-fitting.
8. A grass-cutting head according to claim 1, wherein said sliding
actuating member is made as one piece with said flexible membrane
which has an annular extension, means for securing the flexible
membrane to said container being arranged along an edge
thereof.
9. A grass-cutting head according to claim 8, wherein said securing
means consist of a substantially rigid annular portion fixed to
said cover.
10. A cord-type grass-cutting head including:
a container;
at least one reel of cutting cord housed in said container with
ends of said cutting cord projecting out from holes in said
container;
a cover arranged on said container;
at least one aperture with an edge portion in said cover;
operating means for controlled unwinding of said cord from said
reel, said operating means including a sliding actuating member
which projects out from said container through said at least one
aperture so that a slit is formed between said edge portion of said
at least one aperture and said sliding actuating member, said
sliding actuating member including a sleeve and a plate piece;
a flexible membrane having an inner rim connected to said plate
piece and having an outer rim connected to said cover along said
edge portion, said flexible membrane sealing said slit thus
preventing penetration of waste matter into said slit so that the
aperture is completely sealed, while permitting the sliding of said
sliding actuating member by flexural deformation of said membrane.
Description
DESCRIPTION
1. Technical Field
The present invention relates to accessories for shrub-clearing
devices.
More particularly, the present invention relates to a cord-type
grass-cutting head of the kind comprising a container or housing,
having arranged inside it at least one reel of cutting cord, the
ends of which emerge from holes in said container, and operating
means for controlled unwinding of said cord from said reel, which
means comprise a sliding actuating member projecting from the
bottom part of said container.
2. State of the Art
So-called grass-cutting heads equipped with cutting cords
projecting from the head are commonly used for cutting grass or
shrubs. The head is fitted to the rotating shaft of a
shrub-clearing device and is made to rotate at high speed so that
the cutting cords radially projecting therefrom act on the
vegetation causing cutting thereof.
The cutting cords wear with time and consequently grow shorter. As
a result, they must be restored to their working length, by
unwinding them in a controlled manner from one or more reels housed
in the head container. Several mechanisms have been designed to
perform this function, some being automatic (based mainly on
centrifugal force) and others manual.
Of these, particularly common are mechanisms which have an
actuating member in the form of a cursor or pommel which project
from the bottom of the container inside which the reel of cord is
housed. During operation, the length of the cord may be restored or
modified by pressing the grass-cutting head on the ground so as to
push the cursor inwards and thus actuate the members for
lengthening the cord.
Grass-cutting heads of this type are described for example in U.S.
Pat. No. 5,095,688, U.S. Pat. No. 4,893,410, U.S. Pat. No.
4,882,843 and U.S. Pat. No. 4,823,465.
These heads have the drawback that waste matter from the ground
easily penetrates into the slit between the container and the
cursor which projects from it and slides relative thereto. This
waste matter, consisting of earth and fragments of vegetation, has
a high moisture content and, once it has penetrated into the
container containing the reel of cord, accumulates there until it
blocks up the cord lengthening mechanisms. In order to restore the
device to working order, the head must be disassembled and cleaned
internally.
OBJECTS AND SUMMARY OF THE INVENTION
The object of the present invention is to provide a grass-cutting
head of the type mentioned above which does not have the drawbacks
described.
More particularly, the object of the present invention is to
provide a grass-cutting head with cord lengthening mechanisms
having a member or cursor projecting from the head, in which the
accumulation of waste matter is prevented or substantially
limited.
These and further objects and advantages which will become clear to
persons skilled in the art from a reading of the text which follows
are substantially obtained by means of a flexible protection
membrane which covers the slit between the sliding member and the
container. The membrane allows sliding of the member and at the
same time prevents waste matter from penetrating into said
container.
Although the sliding operating member for lengthening the cord is
normally located in the bottom zone of the head, and in this
position the protection member is particularly advantageous, the
same type of membrane protection may also be applied onto the top
zone of the head, in the case where the sliding member is located
on this side, for example so as to be operated by pressure of the
foot.
Further advantageous features and embodiments of the head according
to the invention are indicated in the accompanying claims and will
be described with reference to some examples of application.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood with reference to the
description and the accompanying drawing which shows a practical
non-limiting example of the invention itself. In the drawing:
FIG. 1 shows a first embodiment of the invention;
FIG. 2 shows a second embodiment of the invention;
FIG. 3 shows an embodiment where the membrane is in the form of an
accessory to be fitted onto existing heads;
FIG. 4 shows a further embodiment in which the membrane is made as
one piece with the bottom portion of the container;
FIG. 5 shows an embodiment in which the membrane is made as one
piece with the sliding member and with the wall of the
container.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
FIG. 1 shows application of the invention to a grass-cutting head
of the type described in detail in U.S. Pat. No. 5,095,688. The
parts of the head which are of no interest in the description of
the present invention, and operation thereof, will be described
only briefly. For a more detailed description, reference should be
made to the publication mentioned above.
The grass-cutting head, generally denoted by 1, has two covers 3, 4
which define a container, housing inside it a reel 5 onto which a
cutting cord F is wound. The ends of the cutting cord emerge from
the container 3, 4 through holes formed in perimetral bushes 7 and
form the elements which act on the vegetation so as to achieve
cutting thereof.
The top cover 4 has internally a sleeve 4A forming a seat 4b for a
pin 9 for connection to the rotating shaft of the shrub-clearing
device (not shown). The connection may be a screw-type connection,
for example consisting of a threaded male member formed on the
driving shaft and a female thread 9A formed in the top end of the
pin 9. A portion 9B of the pin 9 has a polygonal cross-section for
providing a form-fitting twisting connection between the pin 9 and
the container 3, 4.
The bottom cover 3 has an inset lower seat 3A, from the end wall 3B
of which there extends a cylindrical wall 3C with a plurality of
slits 3D. The cylindrical wall 3C terminates at the bottom in an
annular portion 3D, from where an additional cylindrical wall 3E
coaxial with the wall 3C and terminating in a flange 3F
extends.
The annular end portion 3D has integral with it studs 11 which are
inserted into corresponding seats 13 formed in the top cover 4, so
as to provide a twisting connection between the two covers 3,
4.
In the seat defined by the cylindrical walls 3C, 3E and by the
annular end portion 3D there is housed a helical compression spring
15 which acts against the annular portion 3D and a sliding member,
or cursor, formed by a sleeve 17 and a plate-piece 19. The sleeve
17 has radial teeth 21 which slide in the slits 3D of the
cylindrical wall 3C and project from it radially so as to
co-operate with two series of staggered teeth 5A, 5B formed on the
internal wall of the reel 5. The sleeve 17 and the plate-piece 19,
together with the helical spring 15, are retained by a screw 23
which engages in an axial threaded hole of the pin 9.
That which has been described hitherto is already known from U.S.
Pat. No. 5,095,688. Lengthening of the cutting cord F is performed
by pressing the plate-piece 19 on the ground, overcoming the force
of the spring 15 and thus causing upward sliding of the sliding
member formed by the sleeve 17 and the plate 19. As a result, the
teeth 21 of the sleeve 17 are disengaged from the teeth 5B of the
reel 5 and engage with the teeth 5A which are staggered by half a
step. The centrifugal force acting on the cord F causes a
corresponding rotation of the reel 5 by half a step. When the
grass-cutting head 1 is again raised from the ground, allowing the
outward travel movement (limited by the screw 23) of the
plate-piece 19 and the sleeve 17, the teeth 21 disengage from the
teeth 5A and engage with the teeth 5B, with a consequent further
rotation, by half a step, of the reel 5 and a corresponding
lengthening of the cord F.
The operation is repeated the number of times necessary to restore
the cord F to its desired length.
In order to prevent penetration of waste matter into the space
between the plate-piece 19 and the seat 3B formed by the bottom
cover 3 defining the container of the reel 5, a conically extending
flexible membrane 31 is provided. The membrane 31 is integral with
two cylindrical portions 33, 35 with a diameter corresponding to
the diameters of the larger base and smaller base of the conical
surface of the flexible membrane 31. The cylindrical portion 33 is
force-fitted or in any case fixed (for example by means of gluing)
in the seat 3A of the bottom cover 3 of the container 3, 4. The
cylindrical portion 35 is fixed to the inside of the plate-piece
19.
The assembly consisting of the membrane 31 and the two cylindrical
portions 33 and 35 may be obtained as a single moulded piece, using
preferably two materials of different rigidity. The membrane 31,
which may also have a smaller thickness, is made of more flexible
material, while the cylindrical portions 33, 35 are made of rigid
or semi-rigid material. Alternatively, the entire assembly 31, 33,
35 may be made using the same material, if necessary in variable
thicknesses. In this case the cylindrical portions 33, 35 are fixed
to the cover 3 and to the plate-piece 19 for example by means of
gluing or by means of welding or in some other suitable manner.
The conical flexible membrane 31 allows the movement of the sliding
member 17, 19 and hence lengthening of the cord F, preventing the
penetration of waste matter inside the container consisting of the
covers 3, 4.
In FIG. 2, where identical numbers indicate parts which are
identical or correspond to one another, the membrane 31 is integral
with a cylindrical portion 33 which adheres to the cover 3, while
on the opposite side it is formed as one piece with the plate-piece
19, for example in a single injection-moulding operation, using
plastic materials with suitable characteristics (rigidity,
flexibility, thickness).
FIG. 3 shows application of the invention to a grass-cutting head
with a simpler structure. The two covers forming the container of
the head 1 are again indicated by 3 and 4, and 5 again denotes the
reel of cord F which emerges with its ends from the bushes 7. 10
schematically denotes the end part of the driving shaft of the
shrub-clearing device (not shown) which engages in a threaded hole
of the top cover 4.
The reel 5 has upper and lower staggered teeth 5A, 5B which
co-operate with teeth 4X, 3X of the top and bottom covers,
respectively. 15 denotes a helical spring which presses the reel 5
downwards. The reel 5 rests on a sliding member 117 which emerges
from the bottom of the cover 3. The sliding member 117 may also be
formed as one piece with the reel 5.
In order to avoid penetration of waste matter into the space
between the sliding seat of the sliding member 117 and the
cylindrical wall of the latter, a protective membrane 131 of
approximately conical shape, integral with an annular base flange
133 and a disk 135, is fitted onto the external surface of the
bottom cover 3. The annular flange 133 and the disk 135 are made of
material which is more rigid and stronger than the material forming
the membrane 131. The three components 131, 133, 135 may
nevertheless be formed by means of moulding in a single mould using
different materials.
The annular flange 133 serves for fitting the membrane 131 to the
bottom portion of the container 3, 4. Fitting may be achieved in
various ways, for example by means of screws, as schematically
indicated by 136, or by means of gluing or moulding. Alternatively
an annular seat for force-fitting the annular flange 133 may be
provided on the external bottom surface of the cover 3.
The membrane 131, together with the flange 133 and the disk 135,
may be also provided in the form of a kit for impromptu fitting to
an existing head which has no protection. In this case, the flange
131 may be provided, for example, with holes for self-threading
screws for fitting to the cover 3, or else a pressure adhesive,
suitably protected by a protective sheet to be detached at the time
of use.
FIG. 4 shows a variation of embodiment of FIG. 3, where the
flexible membrane 131 is without an annular flange 133 and is
formed as one piece from the bottom cover 3, using a soft and
flexible material which is injected into the mould together with
the more rigid and stronger material which forms the bottom cover 3
and, if necessary, the plate-piece 135.
In the embodiment shown in FIGS. 3 and 4, the membrane 131 may also
be made of the same material which forms the disk 135 (FIG. 4) or
of the same material which also forms the plate-piece 135 and the
annular flange 133 (FIG. 3). In this case, a different resistance
and flexibility may be obtained with different thicknesses of the
various parts 133, 135, 131. If a greater resistance to wear is
dispensed with, the parts 131, 133, 135 may also all be made of
flexible material, in which case the protection assumes the form of
a flexible protection cover, the annular edge of which forms the
actual protective membrane.
FIG. 5 shows a further embodiment in which the flexible membrane,
again indicated by 131, is made as one piece with the bottom cover
3 and the sliding member 117. In this case, both the base flange
133 and the plate 135 are missing.
It is understood that the drawing shows only an example provided by
way of a practical demonstration of the invention, it being
possible for variations to be made to the forms and arrangements of
said invention without thereby departing from the scope of the idea
underlying the invention itself. The presence of any reference
numbers in the accompanying claims merely has the purpose of
facilitating reading of the claims with reference to the
description and the drawing and does not limit the scope of the
protection represented by the claims.
* * * * *